WASHINGTON – President Bush accepted the resignation of White House counsel Harriet Miers yesterday as he remakes his legal team to prepare for what aides expect to be a sustained struggle with a Democratic Congress eager to investigate his administration.

Miers, a longtime Bush loyalist whose nomination to the Supreme Court in 2005 was withdrawn as a result of conservative opposition, led an office that will oversee the legal clashes that could erupt if Democrats aggressively use their new subpoena power.

Bush advisers inside and outside the White House concluded she was not equipped for such a battle and that the president needed someone who can strongly defend his prerogatives.

The White House did not announce a replacement but has settled on a lawyer to take on the assignment, according to several advisers who did not disclose the name. Four other lawyers have been hired as associate counsels in recent weeks to fill vacancies, and White House officials have discussed expanding the office, which is far smaller than it was under President Clinton, who faced legal battles on multiple fronts. With its recent hires, the counsel's office now has about a dozen lawyers.

The search for a new legal team anticipates a spate of congressional demands for information on politically sensitive topics such as whether officials authorized the abuse of U.S. detainees, whether the administration turned a blind eye to profiteering by politically connected contractors in the Iraq war, how the White House responded to Hurricane Katrina, and whether senior officials complied with the law in ordering heightened domestic surveillance.

At the Justice Department, lawyers in the Office of Legal Counsel have been meeting with attorneys from other agencies to discuss potential points of conflict with Congress and to map out legal strategies for responding to demands for documents and testimony, according to several officials.

Republican advisers have been telling the White House to be ready for war, and many focused on Miers as the wrong general. “The White House knew they needed to get a tough street fighter, that's what this is about,” said one such adviser, who spoke on condition of anonymity to preserve access to the White House.

Miers, Bush's personal lawyer in Texas, is popular in the West Wing and admired for her hard work, loyalty and character. But since taking over last spring, White House chief of staff Joshua Bolten has privately expressed doubt that she was right for the job, according to current and former officials.

“We're entering a new era here in the White House and they both came to that conclusion,” a senior administration official said.

Miers had told colleagues she planned to stay until the end of the administration, but after several conversations with Bolten in the last week, agreed it was time to move on.

White House press secretary Tony Snow praised Miers as “an extraordinarily wonderful human being” and “ferocious defender of the Constitution” who was leaving because she has been in the White House for six years.

In a letter to Bush released by the White House, Miers offered expansive praise for the president while never explaining her departure.